Single inverter controller for elevator hoist and door motors

ABSTRACT

A single inverter ( 8 ) provides variable frequency, variable voltage current output ( 11 ) to either a hoist motor ( 3 ) or a door motor ( 6 ), depending on the operating mode of the elevator car ( 1 ). A controller ( 9 ) provides an input signal ( 12 ) to an actuator ( 10 ) for switching the output current ( 11 ) between the motors ( 3, 6 ) by a relay switch ( 12 ). The controller ( 9 ) includes separate control profiles depending upon which motor ( 3, 6 ) is connected to the inverter ( 8 ).

TECHNICAL FIELD

This invention involves an elevator in which the elevator hoist motorand the door motor utilize controlled alternating current power.

BACKGROUND

Elevator cars are typically moved by a hoist motor and the car doors areopened and closed by a door motor. The proper voltage and frequencycurrent is provided by a hoist motor inverter to the hoist motor basedon instructions from a hoist motor controller, and the proper voltageand frequency current is provided to the door motor by a door motorinverter based on command input from a door motor controller.

There are instances where the hoist motor and the door motor areoperated simultaneously to increase a car's operating efficiency. Forexample, immediately before the car reaches or leaves a floor, the doormotor is driven along with the hoist motor. Also, releveling (aligningthe floor of the car with the floor at the entrance) may be performedwhile doors are opened.

Thus, while high performance, general-use elevators may require that thehoist motor and the door motor be driven simultaneously to increaseoperating efficiency, certain home elevator applications do not requirehigh operating efficiency. For such elevators, the need to provideseparate hoist motor inverters and door motor inverters has contributedto the cost of the product.

What is needed is a means for decreasing the overall cost of a homeelevator, or the like.

SUMMARY OF THE INVENTION

In order to accomplish this purpose, this invention is equipped with ahoist motor that moves a car, a door motor that opens and closes the cardoor or doors, an inverter section that simultaneously controls thevoltage and frequency of the current provided to the hoist motor and thedoor motor, and a control section that sends instructions to thisinverter section to control the speed at which the car travels and thespeed at which the door opens and closes. It is constituted so that theproper voltage and frequency current will be provided to the hoist motorfrom the inverter section until the car reaches a floor; and, after thecar reaches a floor, the proper voltage and frequency will then beprovided to the door motor from the same inverter section.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram that shows one application example of anelevator associated with this invention.

DETAILED DESCRIPTION

Referring to FIG. 1, elevator car 1 is driven in a hoistway (not shown)and includes a horizontally sliding door 5 driven by door operator motor6. The car 1 is positioned vertically by means of a rope 2 attached tothe car 1 and suspended from the elevator drive sheave 3 a. The rope 2terminates at its other end at a counter weight 4 which provides abalancing of the vertical forces on the car 1. Drive sheave 3 a isrotated by hoist motor 3 which turns an intermediate shaft 3 b as shown.

Both the hoist motor 3 and the door motor 6 are variable voltagealternating current motors which may be precisely controlled for speedand position by varying the voltage and frequency of the supplied motorcurrent.

According to the present invention, three phase variable frequencyalternating current is supplied to either the hoist motor 3 or the doormotor 6 by a controlled inverter section 8 which receives fixed voltagealternating current from a power source 7, such as an electric utilitysupply line. The voltage and frequency of the output current on lines 21from the inverter section 8 is controlled in response to the inputs froma controller 9 as shown in the figure.

During vertical movement of the elevator car 1, doors 5 are closed andthe inverter section 8 supplies variable frequency and voltage currentto the hoist motor 3, only. The speed and position of the car 1 arecontrolled by the controller 9 so as to precisely deliver the elevatorcar, and its passengers, to the desired floor in the building served bythe elevator. Upon arriving at the desired floor level, controller door9 causes the elevator hoist motor 3 the cease operation and initiates asignal 22 to a relay control 10 actuating the power relay 12. Powerrelay 12 is operated, in response to the actuator 10, to switch theoutput 11 of the inverter section 8 from the hoist motor 3 to the doormotor 6. After the inverter 8 is connected to the door motor 6,controller 9, using a completely different velocity profile, drives thedoor motor 6 to open the doors to permit ingress and egress of thepassengers to the elevator car 1.

It would be appreciated by those skilled in the art that the controlsignals provided to the inverter 8 by the controller 9 will differ inresponse to the controllers selection of either the hoist motor or thedoor motor for receiving the inverter output 11. Thus, a single inverter8 and controller 9 may be used to control both a hoist motor 3 and adoor motor 6 in an elevator application. Switching relay 11 prevents thesimultaneous connection of the hoist motor 3 and the drive motor 6 tothe inverter 8.

The system according to the present invention thus eliminates the needfor a second inverter and controller as is known in the prior art, inexchange for the requirement that the single remaining inverter 8 driveonly one of the hoist motor and the door motor at a given time.

In the event the elevator car were to become misleveled during a periodof time in which the door motor 6 was in operation or the doors 5 in anopen position, a controller 9, sensing the misleveling of the elevatorwith the desired floor, would direct inverter 8 to power door motor 6 soas to close doors 5, then command actuator 10 to actuate the relay 12 soas to connect the inverter 8 to the hoist motor 3 and disconnectinverter 8 from door motor 6. The controller 9 would then control theinverter 8 so as to drive hoist motor 3 to position the elevator car 1at the correct position within the hoistway.

Relay 12, shown here schematically as a mechanical relay having amechanical actuator 10, may alternatively be an electronic switch or anyother device or structure which can divert the output 11 of the invertersection 8 between either the hoist motor 3 or the door motor 6, inresponse to signal 22 from the controller 9.

What is claimed is:
 1. Means for providing variable frequencyalternating current for driving an elevator hoist motor and an elevatordoor motor, comprising: a controller for controlling the elevator hoistmotor to position an elevator car with a hoistway and for controllingthe elevator door motor to open and close an elevator door; a singleinverter section for receiving alternating current from a supply sourceand delivering variable frequency, variable voltage driving current inresponse to a control signal received from the controller; means forswitching the variable frequency, variable voltage current delivered bythe inverter between the hoist motor or the door motor; and meansresponsive to a second signal from the controller for causing the switchmeans to connect the inverter output to either the hoist motor or thedoor motor individually wherein the controller initiates the secondsignal upon sensing the elevator car has reached a desired landing, andwherein the controller initiates the second signal upon sensing theelevator car is misleveled to cause the means for switching to connectthe inverter to the hoist motor.
 2. The means for providing variablefrequency alternating current as recited in claim 1, wherein thecontroller includes a first control profile for use only when theinverter output is connected to the hoist motor, and a second controlprofile for use only when the inverter output is connected to the doormotor.
 3. The means for providing variable frequency alternating currentas recited in claim 2 wherein said controller automatically switchesfrom the first profile to the second profile when the inverter isconnected to the door motor.
 4. The means for providing variablefrequency alternating current as recited in claim 1 wherein saidcontroller automatically switches from the second profile to the firstprofile when the inverter is connected to the hoist motor.